Download callback refactor

[VilppeRiskidev]

No description provided.

[VilppeRiskidev]

I based this branch on the previous branches since those have been approved already and are just waiting to be merged.

[anttimaki]

The changes look good 👍🏻 I still found some reasons to flap my gums so read the commits for future reference.

[anttimaki]

Food for a thought, not a change request:

Given that this is in the end a rather simple piece of code, it could be argued that having it in the utils is a bit of overkill, especially since we have another wrapper in the mixin that reduces duplication. Another thing that IMO speaks a bit against having it here is the fact that we need to pass the store as an argument. That's not inherently bad, but a weak signal that the split between UI component and helper library should be considered. For example, this helper is now not reusable if the call site doesn't have access to the store. Ideally we could import the store singleton to helpers but I think that's currently unnecessarily difficult due to R2MM & TSMM having different store definitions.

I guess that my point is that I've no strong arguments one way or another, but my nitpick level opinion is that passing the store as an argument should be avoided if it's easy to do so.

[anttimaki]

Just mentioning this in the hopes we remember to do this in the future PRs: this should be something like isDownloadProgressModalOpen and probably to be handled into ModalModule store. Ideally in a way that when one of the three modals in this file is opened, the other two are automatically closed.

[VilppeRiskidev]

#1587
#1590
^Many of the changes have been reviewed in these PRs.

[VilppeRiskidev]

Rebased